Breaking Down Anaphylaxis
May 22, 2025
The pot and the kettle - Anaphylactic vs Anaphylactoidπ«β«
Anaphylaxis is just that - isn’t it? Not quite… There are ‘allergic’ and ‘non-allergic’ reactions, known respectively as anaphylactic and anaphylactoid reactions. Let’s break it down! π§ͺ
𧬠Anaphylactic (Allergic) -
This is an immune IgE mediated allergic reaction involving the release of mast cells and basophils in response to an allergen. 𧫠This response involves prior exposure and sensitisation to an allergen where the immune system produces specific IgE antibodies to the triggering agent.
𧬠Anaphylactoid (Non-allergic) -
The term anaphylactoid has fallen out of favour in recent years, now preferably termed non-IgE mediated anaphylaxis. β As the name suggests, direct activation of mast cells and basophils occurs without the presence of IgE antibodies. With this type of reaction, there does not need to be any prior exposure to the triggering agent. β οΈ
π©Ί What does this mean clinically?
In the immediate phase of the initial reaction, the clinical features are almost identical and are both life threatening β‘, requiring treatment following an anaphylaxis protocol. π¨
The importance of identifying which reaction has occurred comes into play down the track when determining lifelong management strategies for the patient. π§ π
For anaphylactic reactions where it is determined there are IgE antibodies, there is a high risk of anaphylaxis recurrence with any exposure to the triggering agent. π Allergy testing π§ͺ can be done to determine specific triggers and develop an allergy management plan. ππ Strict avoidance π« of the allergen is the only way to manage the allergy ongoing.
For non-IgE mediated reactions, the response is generally dose dependent π, and not a true allergy. Future reactions can be offset or completely avoided by utilising pre-medication π prior to exposure, for example, corticosteroids prior to contrast dye. 𧴠Ongoing management does not need to be as strict as anaphylactic reactions and allergy testing is not necessary.
π§ How does this impact your practice?
Remember - in the immediate scenario of anaphylaxis, rapid treatment is essential πβοΈπ and is the same regardless of the type of reaction that has occurred.
When caring for a patient who has previously had an episode of anaphylaxis, the type of reaction can change the course of the patient’s treatment through their perioperative phase. π₯ Triggering agents might need to be completely avoided π, or may still be used with pre-medication in place to prevent reaction if there is no ‘true’ allergy identified. π§βοΈ
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References:
Lagopoulos, V., & Gigi, E. (2011). Anaphylactic and anaphylactoid reactions during the perioperative period. Hippokratia, 15(2), 138–140.
Mills, A.T.D.,Sice, P.J.A.,Ford, S.M. (2014). Anaesthesia-related anaphylaxis: investigation and follow-up. Continuing Education in Anaesthesia Critical Care & Pain, V14(2), Pp 57–62. https://doi.org/10.1093/bjaceaccp/mkt034
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